Air Con Temp Switch

[marinabrid]

hi all

another saga of no cool air, after weeks of trying to sort it, i had another mobile chap say compressor is working ok everthing is sound full of gas no leaks new dryer but still i get no cold air the pipes from the compressor are not cold at all but this guy puts his machine on and says its working fine and hes stumped.

mention something about an outside air temp switch that may be faulty but he or i cant see one, anyone any idea where this is on the mk1 tdi, or anyone out there with any more ideas on this. thanks again

[MrT]

The only electrical control to the air conditioning unit is the power that engages the compressor. If the compressor is engaging and there is no cold air, the probelm is mechanical and not electrical. You first need to check that the compressor is engaging and disengaging when told to do so by the controls, the easiest way to do this is to listen for a clunk and a drop in revs when the airconditioning engages and the rise when it disengages. You can also see the centre of the compressor turning when it is engaged. If this is happening, then your problem is not electrical.

 

If the compressor does not engage, then start looking for an electrical problem or a failed compressor clutch. The first thing to check is the power supply to the compressor clutch which is only two wires, if you have 12V here, when the air-con is meant to be on, but the air con is not working, then the problem is the clutch or another mechanical failure. If you do not get the 12V to the compressor when the air con should be running, then you need to start looking at the electrical system.

[matt1003]

its in the lower part of the front bumber in the grills looks circular with a pin in the middle of it

but if you have the climate control on the car it should display the outside temp on there

just compare with the weather to see if its about the same

matt

[marinabrid]

thanks for advice,, the compressor is working according to mr cool the aircon man it clicks in, the centre clutch is spinning or if engine not on it can be turned by hand with some resistance, though no cold pipes, the air con man is at a loss. its had a new dryer only this year a full regass etc pulling what bit of hair i have left out now. one thing noticed is that the compressor clicks in rather queitly rather with a loud clack, mr cool put his machine on and he said the compressor is working as it should. odd very odd

[insider]

Perhaps a second opinion from another "mr cool"?

[marinabrid]

thought of that but all these call outs add up . anyone out there had anything similar ?

[MrT]

As the clutch is being switched on and off, the electrical system is doing its job, so that is not your main problem. If no pipes are getting cool the system is not compressing and decompressing the refrigerant.

 

This can only be due to either the system being blocked which is very unlikely, the compressor not working properly or insufficient refrigerant.

 

Too much refrigerant would stop the system from running as the pressure sensor would stop the compressor from being switched on or it would turn on and off every few seconds. A severe lack of refrigerant would also trigger the pressure switch and stop the compressor being switched on, but the system would fail to cool long before that happened.

 

If pipes get cool but the car doesn't you have have stuck air distribution flaps or blocked airways.

 

If your compressor centre turns but there is no noticeable drop in engine revs (it is a small drop but the change in note can be heard) due to the load when it engages, this would point to a broken compressor shaft or other compressor failure

 

My system behaved this way and even with dyes and pressure tests no leak could be found. The system would work after a regas and just get weaker over a few weeks. There was a microscopic leak on the condenser at the top of the dryer, (where it normally occurs due to faulty design and corrosion on the early Mark 2s), but it was only eventually found after the system was dismantled to replace the compressor due to a total clutch failure. When I looked at prices just over a year ago, it was cheaper overall to buy and have fitted a re-manufactured compressor than it was to buy and fit a new clutch.

 

I seem to remember recently some large chain offering no charge if their regas did not make the system cooler. It was Quickfit, ATS, Halfords or similar.

[marinabrid]

thanks ive turned the comp on and off a lot of times and there is no drop at all in rpm so i think the kapoot compressor is favorite particulary as the pipes aint getting cold thanks again

[seatkid]

another mobile chap say compressor is working ok everthing is sound full of gas no leaks new dryer but still i get no cold air the pipes from the compressor are not cold at all but this guy puts his machine on and says its working fine and hes stumped.

 

Anyone who tells you its working fine despite no cold air is an idiot. ;) You shouldnt pay him!

 

As I said in one of your previous posts - you should measure the voltage at the compressor connector (with the compressor still connected though!) - with the engine running this should read 13+ volts. If it is much lower, then the compressor clutch wont engage fully. You could also check the electrical resistance of the clutch to check the windings in the clutch.

 

What I am getting at is the problem is probably the compressor clutch.

 

Go to kwikfit and let them have a go - there's no charge if it doesn't work - their machines are the correct type (computerized and no sight glasses!) and they will give you a report that details system pressures both on the hi and lo sides before and after as well as system gas weights.

 

From the pressures you will be able to ascertain if the compressor is working or not (mine gave 15 bar at hi port and 2.2 bar at lo port when running)

[marinabrid]

i got some readings on the printout i got

stationary low side 75 stationary high side 75psi

 

running pressure low side 30 psi

running pressure high side 85 psi

 

does this make any sense is it in or out of whats needed to cool me,

your right though if an engineer cant say if the compressor is knacked he must be knacked himself

[seatkid]

stationary pressures maybe a little high but OKish. Did he give a figure of gas weight put in? (should be 950g)

 

Running - lo is OK but high side is too low - mine in comparison is 220 psi

 

Possibilities:

 

1. Compressor knacked (internal seals gone)

 

2. Expansion valve is stuck (open) - this is located on the high pressure side of the evaporator - possibly due to debris.

 

3. Compressor clutch slipping (but I think you would get a strong smell and smoke)

 

Take your pick.......

[marinabrid]

looked on the readout 950g of gas went in. what i notice though , when i turn air con on after engine has run for 10 mins is that when the compressor clicks in there is indeed a drop in rpm, however this is short lived. if i turn it off then back on and off a few times more there is no drop at all in rpm and the click is very quiet, so i think we must assume its kapoot. you agree ?

[MrT]

That depends if it clicked in the first time and worked but soon died and that is repeatable after leaving for some time, or if from now on every time it clicks in it doesn't cause the drop in revs. If it only dropped revs once and never again, that points to a leak somewhere, i.e. it works whilst full of gas but when some has been lost it will never work again until a re-gas. A good air-con engineer would have weighed the gas before and after their work, if they needed to add a lot after all the work that had been recently done, that would again point to a leak. The way it worked pn;y once, sounds more like a leak than a compressor failure.

 

Also if you have the dual air-conditioning, that is with the vents in the roof lining for the rear seats, you need a lot more gas than the normal system.

[marinabrid]

mmmm it clicks in and drops revs 1st time but it still doesnt blow cold on first click in, it clicks in and stays warm. then after it stays warm as well. no leaks detected. hes done test for leaks with the dye and it aint lost no gas or pressure in a week. why do we bother ?

[Bigjeeze]

Something ain't right!! It seems you've checked everything - If it is maintaining pressure then it is either the compressor or one of the switches. If as you say it affects the revs when first turned on it does snound like the compressor is working. Maybe the flaps are stuck - Get a VAG com on it to see what faults come up.

[marinabrid]

think i may have explained it wrong. first start up on morning if i turn air con on then there is a drop in revs as it clicks in but there is no cold air at all, even for a second or two, nothing. then if i turn it off and back on the revs dont drop at all, unless the car has been standing for many many hours. if it has then the revs drop again.

but if you leave it for a few mins the thing clicks in queitly but with no rev drop.

how would i know if any other part had failed, like this expansion valve or condenser, would there failure cause symtomes i describe ? thanks for all advice

[MrT]

You would need the double pressure testing setup to detect a stuck expansion valve, but this is very unlikely unless you have had a major compressor failure where debris has been spread around the system.

 

A condensor failure would be a leak in the condensor, detectable by dye and a pressure soak test, although mine was not clearly shown up by this.

 

A compressor or compressor clutch failure again can usually be shown by a proper pressure test.

 

Again the most likely problem is a leak which the Galaxies are notorious for. If it is not an obvious leak, the only way to tell is by having it correctly filled then after a period having the gas removed and reweighed to see how much has leaked out.

 

VAG-COM will not tell you anything much about the mechanical side of the system, it will tell you if you have had an over or underpressure alarm, various temperatures and distribution (flap) positions, but not what is causing the problems you describe.

 

Any reputable air conditioning specialist should be able to work out what your fault is. Keeping paying for re-gases and examinations with cheaper "specialists" will work out more expensive in the longer term and without specialist equipment, a DIY solution may not be possible. Even if you could diagnose a compressor failure yourself and decide to change it, you would not be able to vacuum out the system (essential), fully re-gas and oil and pressure test it yourself. It should not be hard to find a good specialist who will charge a diagnosis charge and will then take this off the bill if you decide to let them fix it.

[marinabrid]

does this explain anything,, i put a gauge on the low pressure side and i noticed that its in the correct area for pressure but the needle keeps going up and down in the correct area 25-45 psi every few seconds, does this indicate anything or should the pressure remain constant ?

[MrT]

It will change with rpm and may change a little as the temperature of the system varies but it should not be changing every few seconds. You need first to check if the clutch is engaging and disengaging as this happens. If it is, the problem could be the pressure switch operating due to too much or little refridgerent, an electrical fault or even the thermostat controls cycling the system. If the clutch is engaged all the time this pressure change happens you either have very low gas, or a broken clutch and/or compressor.

[jb8306]

Hi There

I have had this problem on my Galaxy when it was still under warrenty. The problem was the external temperature sensor not working correctly, it was stating the temperature was 20 degrees lower than it was. The compressor will not be told to operate under 4 degrees. This temp sensor must be different to the climate control and dash control sensor has these were reading correctly. Hope this helps.

[jb8306]

Hi

Looking on Ford TIS system, temp sensor is listed as part N289 and is mounted under the bonnet RHS by the haedlight unit, it seems to be hear for most models.

[marinabrid]

so is this sensor fitted to all year models without climate control ? ours is a 97 year with manual control

[MrT]

As I have said before there is only one control operating the air con system and that is the 12V to the compressor clutch. If there is 12V to the clutch and the system is not working it has nothing to do with any sensor or switch or any other electrical device. All these devices decide whether to turn the compressor on or off by applying the 12V to the clutch.

 

If you are not getting the 12V to the clutch or the 12V ito the clutch is turning on and off, look at your sensors and electrics.

 

If you have a steady 12V to the compressor clutch look at the air con mechanicals.

 

THERE IS NO OTHER ELECTRICAL INPUT TO THE AIR CON SYSTEM.